📌 POINTS TO PONDER 

🔹Reversal phenomenon is the decline from maximal calculus accumulation. It is due to vulnerability of bulky calculus to mechanical wear from food, cheeks, lips and tongue. 

🔹Calculus can also occur readily in germ free animals. 

🔹Calculocementum is the calculus embedded deeply in the cementum and which appears morphologically similar to cementum. 

🔹Calculus is the most prominent plaque retentive factor and is a secondary etiologic factor for periodontitis.

🔹It can also occur readily in germ-free animals. 

📌 VIVA VOCE 

Q1. What is the reversal phenomenon of calculus? 

Ans. Reversal phenomenon is the decline from maximal calculus accumulation due to vulnerability of bulky calculus to mechanical wear from food, cheeks, lips and tongue. 

Q2. Why subgingival calculus is dark green or dark brown in color? 

Ans. Subgingival calculus is dark green or dark brown in color because of the presence of blood products (iron heme pigments) associated with subgingival  hemorrhage. 

Q3. Why supragingival calculus forms most readily on the lingual surface of lower anterior teeth? 

Ans. Supragingival calculus forms most readily on the lingual surface of lower anterior teeth due to following reasons: 

• Abundant supply of urea from the major salivary gland (submandibular gland) secretions tends to increase pH in plaque and promote calcium and phosphate ions precipitation. 
• Due to the presence of submandibular gland Wharton’s duct on the lingual surface of lower anterior teeth, higher salivary film velocity promotes clearance of acid and salivary sugar from plaque leading to higher pH of lingual area. 

Q4. Which is the most important plaque retentive factor? 

Ans. Calculus is the most important plaque retentive factor as it retains and harbors plaque on its rough surface. 

Q5. Which mineral is more critical in plaque mineralization? 

Ans. Phosphorus. 

Q6. Who gave the theory “Doctrine of Calculus”? 

Ans. Paracelsus 

Q7. Which explorer is used to detect subgingival calculus? 

Ans. A fine subgingival explorer “TU-17” can detect the subgingival calculus. 

Q8. Name various calcification promoters. 

Ans. Urea, Fluoride, Silicon. 

Q9. Name various calcification inhibitors. 

Ans. Pyrophosphate salts, Zinc salts and Triclosan with a PVM/ MA copolymer. 

Q10. Why the location of calculus does not indicate the bottom of the periodontal pocket? 

Ans. The most apical plaque is not sufficiently calcified to be visible on radiographs.

📌 MULTIPLE CHOICE QUESTIONS (MCQs)

💡 Mineralized plaque is: 

A. Materia alba 

B. Calculus 

C. Food debris 

D. Dental stains

Answer : B 

💡Calculus :

A. Per se is the irritating cause to gingiva 

B. It is always covered with a non-mineralized layer of plaque 

C. It is formed as all plaque undergoes mineralization 

D. Formation cannot be maintained in germ-free animals

Answer : B 

💡The most efficient means of identifying supragingival calculus is by: 

A. Visual observation and compressed air 

B. Tactile detection and periodontal probe 

C. Use of disclosing solution 

D. Transillumination

Answer : A 

💡Dental calculus contains: 

A. Vital microorganisms 

B. Non-vital microorganisms 

C. Both of the above 

D. None of the above

Answer : B 

💡The most common crystalline forms present in supragingival calculus are: 

A. Hydroxyapatite and magnesium whitlockite 

B. Hydroxyapatite and octacalcium phosphate 

C. Hydroxyapatite and brushite 

D. Magnesium whitlockite and octacalcium phosphate

Answer : B 

💡 Which of the following crystals is more commonly found in the calculus of mandibular anterior areas? 

A. Hydroxyapatite 

B. Magnesium whitlockite 

C. Octacalcium phosphate 

D. Brushite

Answer : D 

💡 Calculocementum is: 

A. Calculus similar in composition to cementum 

B. Cementum similar in composition to calculus 

C. Cementum appearing morphologically similar to calculus 

D. Calculus appearing morphologically similar to cementum 

Answer : D